I suspect many people reading this in Europe or North America share Professor Collier’s scepticism about skilled migration. You are not racist or xenophobic. You are concerned about the plight of the global poor, and you welcome diversity in your community. But you worry that maybe Collier’s right. Maybe the fate of your university-educated Haitian neighbour down the street, earning a good salary and sending her kids to good schools since moving to the UK, is a distraction from, and maybe even a hindrance to, reducing poverty in Haiti.

Before we begin, it’s important to note that we’re not really debating whether the rate of skilled emigration from Freetown to London or Port-au-Prince to Miami is too fast or too slow. We’re really talking about whether to deport your neighbour. Or whether to refuse her a visa in the first place, and consign her and her family to a future of low wage employment, bad schools, and preventable disease “back where they came from.” That is the policy proposal on the table for your consideration.

My argument is that the burden of proof here should be heavy, and it should rest on the shoulders of those who would build walls and tear apart families. If you think the prosecution has met that burden of proof, here are three reasons to reconsider.

Empirically, the alleged “brain drain” from poor countries does not exist.

Prof. Collier worries that while China wins from an emigration “brain gain”, Haiti and other small, poor countries lose out to “brain drain”. So let’s have a look at the numbers. Based on research by economists Frederic Docquier and Abdeslam Marfouk, I compiled a list of the ten lowincome countries with the highest rates of skilled emigration. They are: Haiti (84% of secondary school graduates living overseas in an OECD country circa 2000 – though this exaggerates a bit, by counting Haitians educated abroad), Gambia (63%), Sierra Leone (53%), Mozambique (45%), Liberia (45%), Kenya (38%), Uganda (36%), Rwanda (26%), Guinea Bissau (24%), and Afghanistan (23%).

You might suspect that such high emigration among educated people has led to stagnation or decline in the share of skilled workers. You’d be wrong.

In the low-income countries with the highest levels of skill emigration, the stock of skilled workers left behind is going up, not down. Even after you exclude the migrants, the prevalence of both secondary and tertiary education more than doubled! This simple fact is often lost in fretting over a “brain drain”. Sceptical readers will rightly note that the counterfactual here is unclear: maybe residents’ education would’ve been even higher without emigration. There’s good reason to think the opposite. The opportunity to join the diaspora is a key motivation for pursuing higher education. Multiple studies looking at natural experiments from Cape Verde, to Fiji, to Nepal, have all found that new migration opportunities led to more investment in schooling not only for migrants, but for people who didn’t end up migrating as well.

Emigration is not an alternative to other drivers of development, it is a cause.

Perhaps you feel letting poor people move to better opportunities is a distraction from the real work of promoting development within the geographic borders of poor countries. Rather than migration, we need more aid, more investment, and better governance in poor countries.

Consider Haiti again. The World Bank’s bilateral remittance and migration matrices show that the 670,000 adult Haitians living in the OECD sent home about US $1,700 per migrant per year. That’s well over double Haiti’s US$670 per capita GDP. And Haiti is not unique. On average, across the whole set of lowincome countries, each migrant to the OECD sends home more than double her country’s per capita GDP each year.

Remittances took a dip during the 2008 financial crisis, and have not yet fully recovered, but they still clock in at roughly US$400 billion worldwide, compared to a total foreign aid budget globally of about US$125 billion. It’s true that skilled workers earn more back in Haiti than the unskilled, but they also remit considerably more as well.

Migration and development

And it’s not just remittances. Migrants also significantly boost FDI back to their country of origin. There’s also tantalizing new evidence emerging from various corners of the globe about the effects that migrant diaspora have on home-country governance – some of which (to be fair) are summarized in Exodus. From Mali to Moldova and back to Cape Verde again, there is growing evidence migration exposes citizens to democratic values and strengthens demands for accountability and good governance at home.

There is zero evidence that trapping skilled workers in places with few skilled jobs will generate growth.

The argument put forward in Prof. Collier’s article is that emigration deprives countries of the talented and skilled individuals that will drive broad-based growth. It’s undeniable that education has huge economic and social payoffs for individuals and their families. And we probably all agree that in order for Haiti to grow in the long run, attracting and retaining more skilled workers will be a necessary step. But it’s also clear that education alone is insufficient for economic development without public infrastructure, functioning credit markets, tolerable government, etc…. the sorts of things places like Haiti and Afghanistan often lack. Knowing that those ingredients are lacking, are we confident enough to deny people the right to leave?

Bear in mind there is no study out there, from Haiti or anywhere else, showing any empirical evidence that migration restrictions have contributed to development. So this is a huge, evidence-free gamble we’re taking with other people’s lives. Economist Branko Milanovic estimates that 80% of global inequality is explained by your country of birth. Through education and migration, skilled migrants from low-income countries have struggled to overcome their unlucky draw in this birth lottery. They owe us no explanation. Their success stories are what we mean by development. They’re also a key motivation driving young people in poor countries into higher education, as well as a vital source of development finance far in excess of official aid.

So feel free to oppose immigration from poor countries if you’d like, but let’s not fool ourselves into thinking there’s anything altruistic about that stance.

• JUSTIN SANDEFUR is a research fellow at the Centre for Global Development. His research focuses on the interface of law and development in sub-Saharan Africa. The Centre for Global Development works to reduce global poverty and inequality through rigorous research and active engagement with the policy community to make the world a more prosperous, just, and safe place.